1. Field of the Invention
This invention relates to a seal and anchoring assembly which can be utilized to establish sealing integrity between a tubing string and the bore of a conventional packer in a subterranean oil or gas well.
2. Description of the Prior Art
When conventional packers are utilized in subterranean oil and gas well completions for such purposes as providing a seal between separate producing formations, it is necessary that sealing integrity be established between the inner bore of the packer and the tubing string inserted into the packer. In many applications it is also necessary to secure the tubing string to the packer. This function has generally been performed by use of a conventional anchor seal assembly which utilizes elastomeric sealing elements to establish sealing integrity along the bore of the packer and radially expandable latching collets for engaging the threads which are normally used to set the packer. U.S. Pat. No. 3,229,767 discloses a conventional packer with which conventional anchor seal assemblies can be used. Anchor tubing seal assemblies which can be utilized with the packer disclosed in U.S. Pat. No. 3,229,767 are depicted on page 674 of the 1980-81 Composite Catalog of Oil Field Equipment & Services published by World Oil. These conventional tubing anchor seal assemblies employ elastomeric materials such as nitrile seals or viton seals. These conventional seals can be bonded in place or can comprise a stack of similar sealing elements having a chevron configuration. These conventional tubing seal assemblies also rely upon the inherent resiliency of the sealing elements to provide sealing integrity between the mandrel and the packer bore.
In some applications, for example, where the temperature and pressure are sufficient to cause failure or deterioration of conventional seals, the resiliency in available sealing elements may not be sufficient to establish sealing integrity. One means of establishing this resiliency is to incorporate a spring member into the anchor seal assembly to urge the non-resilient sealing elements into engagement with the packer bore. One example of the use of such spring means is found in U.S. patent application Ser. No. 273,514 filed on June 15, 1981. Of course the need to provide additional spring loading means requires a more complicated structure than is available in conventional anchor seal assemblies. Since the tubing string would generally be subject to unbalanced forces and would be urged in an upward or downward direction it would be desirable to utilize these forces to energize the seal. It would also be desirable to utilize an anchor seal assembly in which the seals are energized due to longitudinal compression regardless of the direction of the force acting on the tubing.